What drives the cost, and how to think about tank size

People want a price, and then a tank size, in that order. The order is backwards, and a price printed here would be stale the week a manufacturer changes it. Check the current price on the manufacturer site when a model actually fits your lab sheet. This page is about what that price is paying for, and about how not to guess the tank.

Why there is no price table

A whole-house system is a heavy piece of equipment with a valve, a tank, and media. Makers change the number. Shipping changes it again. An install quote is local. If this site froze a dollar figure, someone would trust it after it was wrong. We would rather send you to SpringWell, US Water Systems, and SoftPro for the current price of the specific model whose published limits cover your report.

Do not compare those prices until the models are in the same category. An air-injection tank and a peroxide-injection system are not the same line item. The approach guide is the sort. The brand questions are how you confirm the model.

What the quote is actually buying

• The treatment category. Air injection has a tank, a valve, and media. Chemical injection adds a metering pump and a place for the oxidant. A softener, if you still need one for hardness, is another tank, salt or potassium, and its own valve.
• Media volume. A larger bed costs more and can treat a higher flow, up to the service rate the maker prints. It does not raise the chemistry limit. If your iron number is above the published limit, a bigger tank of the same media is still the wrong tank.
• A sediment pre-filter. Some installations need a housing and cartridges ahead of the iron filter so sand and rust particles do not load the bed. That is a repeating cost, not a one-time accessory.
• pH equipment. If the lab pH is outside the filter's printed range, a calcite tank or a chemical pH feed may be required first. Budget it only if the manufacturer says the filter needs it. Do not invent a pH fix from a forum.
• The drain and the install. Backwash water has to go somewhere your local rules allow. A plumber, a new drain, an electrical outlet for a valve or a pump, and a floor that can hold a full tank are part of the real cost. Self-install only saves money if the manual matches your skill and your code.
• Freight. These tanks ship as freight, not as a small parcel. The product page is where that charge either appears or is included. Read it there.

What you keep paying

Air injection usually has no chemical jug. You still pay for water used in backwash, and eventually for media and a valve service. Peroxide or chlorine injection adds the oxidant itself, on a schedule set by your water and the pump's design, plus pump parts. A softener adds salt or potassium chloride for as long as you run it. None of those repeating costs are a reason to skip the iron filter and make the softener do both jobs. A fouled resin bed is its own bill. The softener section explains why.

Tank size follows peak flow, not a hunch

Service flow is the rate, in gallons per minute, at which the manufacturer says the filter can treat water. Your peak demand is the rate you actually draw when the house is busy. The service flow has to be at least that peak. If it is not, pressure drops or untreated water sneaks past the design.

Build the peak from fixtures you really run together, using the flow printed on the fixture when you can find it. A shower head has a number on it or in its manual. A washing machine manual has one. Add the combination that actually happens in your house, such as a shower plus the washer, not every tap in the building turned on by magic. Write gallons per minute. A feeling that the house is "busy" is not a flow.

Bathroom count is a rough clue, and manufacturers use it as a label: one to three bathrooms on one model, four or more on another. Treat that label as their shortcut for a typical house, then check it against your own peak and against the service flow they print in gallons per minute. A four-bathroom house with low-flow heads and one person home at a time is not the same draw as a two-bathroom house that runs both showers and the dishwasher every evening. The label cannot see that. You can.

Backwash is the number people skip

The spec sheet should also list a backwash rate. During the cleaning cycle the control valve sends water backward through the media to lift it and flush solids to the drain. That rate is often higher than a shower. The well pump has to supply it for the minutes the cycle lasts, and the drain has to accept it without flooding.

If the pump cannot make the backwash rate, the bed compacts and channels, and the filter looks installed while it stops working. A larger tank is not a gentle option. A larger bed often wants a stronger backwash, not a weaker one. Ask the manufacturer what backwash flow the model on your quote requires, and compare it with what your pump can deliver. A well contractor can measure that. A product photo cannot.

An order that keeps the money attached to the water

1. Get the lab report and clear any health contaminant with the health department before you price equipment. How to read the report is the sort.
2. Decide whether the smell is the heater, the well, or both. The rotten-egg page is that fork. Do not buy a tank to fix a hot-only anode problem.
3. Choose air injection or chemical injection from the published limits, not from the lowest number on the page.
4. Pick the model whose service flow covers your peak and whose backwash flow your pump can supply.
5. Then check the current price on the manufacturer site, including freight and any pre-filter or pH step they told you the water needs.
6. Add install and the repeating cost of oxidant or salt only after the equipment matches the report.

A tank that is too small for the flow wastes the purchase. A tank that is large enough for the flow and wrong for the chemistry wastes it too. The lab sheet is the expensive part to skip, not the freight.